Download Example 2

Lesson Template – Ben Davis
Subject Area(s)
Chemistry, Physical Science
Associated Unit
Hydrogen as an Energy Carrier
Lesson Title
Hydrogen from Energy
Header
Image 1
ADA Description: Electricity plus two water
molecules turning into two hydrogen
molecules plus an oxygen molecule. Red
spheres are hydrogen, light blue spheres are
hydrogen
Caption: Making hydrogen by using Energy
Image file name:
WaterPlusEtoH2plusO2.bmp
Source/Rights: Copyright © 2009 Benjamin
Davis
Grade Level 8 (8-12)
Lesson # 1 of 2
Lesson Dependency
NONE
Time Required
30 minutes
Summary
This lesson (part one of two) aims to teach students about hydrogen and its role as a fuel
and energy carrier. In this first part of the lesson, students should learn what hydrogen is,
who discovered and named it, what it is used for, and how you make it. In learning about
hydrogen, students should locate its place on the periodic table, identify how many
protons, electrons, and neutrons (0 to 2) it can have, and be able to tell you its physical
and chemical properties. They will learn that you can use hydrogen to run an internal
combustion engine like the one in their car, use it to run a “fuel cell” to make electricity,
use it to propel the space shuttle up into space, and use it to make energy like in the sun.
This lesson gives background to students so that they can do an activity where they
produce hydrogen from water using electricity (electrolysis).
Engineering Connection
Real world engineers are working right now to design new cars and new fueling stations
that use hydrogen. This lesson should expose students to the different technologies that
use hydrogen and the different challenges in designing new devices and machines that
use hydrogen. More explanation of this connection will be given in the second part of the
lesson when students learn about fuel cells.
Engineering Category, if applicable
Relates science concept to engineering
Level of Inquiry
1. Questions – Level 4: Learner poses a question / hypothesis before they begin
2. Evidence – Level 3: Learner directed to collect certain data
3. Explanations – Level 4: Learner formulates explanation after summarizing
evidence
4. Evaluating explanations – Level 3: Learner directed towards areas and sources of
scientific knowledge
5. Communication and justification – Level 1: Learner given steps and procedures
for communication
The lesson can be altered to incorporate more inquiry for more advanced or older
students (less explanation of procedures with more focus on safety, more open ended
questions on what happened in activity, oral or formal written presentation of their
results, etc.) These levels were most appropriate for an average 8th grade physical
science student.
Keywords
Hydrogen, Energy, Electricity, Electrolysis, Oxygen, Proton, Neutron, Fuel, Cell
Educational Standards
1) CA State Standards addressed:
Grade Eight – Science Content Standards
3. Structure of Matter – Each of the more than 100 elements of matter has distinct
properties and a distinct atomic structure. All forms of matter are composed of one or
more of the elements. As a basis for understanding this concept:
a. Students know the structure of the atom and know it is composed of protons, neutrons,
and electrons.
b. Students know that compounds are formed by combining two or more different
elements and that compounds have properties that are different from their constituent
elements.
d. Students know the states of matter (solid, liquid, gas) depend on molecular motion.
e. Students know that in solids the atoms are closely locked in position and can only
vibrate; in liquids the atoms and molecules are more loosely connected and can collide
with and move past one another; and in gases the atoms and molecules are free to move
independently, colliding frequently.
5. Reactions – Chemical reactions are processes in which atoms are rearranged into
different combinations of molecules. As a basis for understanding this concept:
a. Students know reactant atoms and molecules interact to form products with different
chemical properties.
b. Students know the idea of atoms explains the conservation of matter: In chemical
reactions the number of atoms stays the same no matter how they are arranged, so their
total mass stays the same.
c. Students know chemical reactions usually liberate heat or absorb heat.
7. Periodic Table – The organization of the periodic table is based on the properties of
the elements and reflects the structure of atoms. As a basis for understanding this
concept:
b. Students know each element has a specific number of protons in the nucleus (the
atomic number) and each isotope of the element has a different but specific number of
neutrons in the nucleus.
c. Students know substances can be classified by their properties, including their melting
temperature, density, hardness, and thermal and electrical conductivity.
9. Investigation and Experimentation – Scientific progress is made by asking meaningful
questions and conducting careful investigations. As a basis for understanding this concept
and addressing the content in the other three strands, students should develop their own
questions and perform investigations. Students will:
a. Plan and conduct a scientific investigation to test a hypothesis.
f. Apply simple mathematic relationships to determine a missing quantity in a
mathematic expression, given the two remaining terms (including speed = distance/time,
density = mass/volume, force = pressure × area, volume = area × height).
2) National Standards addressed:
Science and Technology in Society
History of Science
Transfer of Energy
Pre-Requisite Knowledge
Students must know: what protons, neutrons, and electrons are, how to find an element
on the periodic table, where the atomic number is and what it signifies, simple algebra as
in x = y x z, what density is and what it means for gases and liquids, how to measure
liquids by volume, what it means to burn something
Learning Objectives
After this lesson, students should be able to:
•
State how many atoms there are in a hydrogen molecule and its chemical
formula
•
List different uses for liquid, solid, and gaseous hydrogen
•
Describe how atoms are rearranged during electrolysis of water
•
Explain one method for making hydrogen gas
Introduction / Motivation
First step: warm-up. What is a chemical reaction? [a process where elements or
compounds undergo a chemical change: atoms are rearranged into different combinations
of molecules] Okay, so now that we know what a reaction is, how does that relate to
electrolysis? [electrolysis is a reaction which uses electricity to force the chemical
change: try to get students to relate it to an “electricity reaction”] Good.
Now, what is electricity, does anybody know how it works? [if not, describe how
electricity works to the students and explain its role as an energy carrier] Electricity is a
flow of electrons. So when you plug something into the wall, electrons come out of the
wall and go through the one end of the plug, up the wire into the lamp (or the cell phone
or the toaster), and then into the circuits inside to make the device work. After they’re
done making it work, they have to go back down the wire through the OTHER end of the
plug, through the wall, down the power lines, and to the power plant where they give the
electrons back the energy that they lost when they made the lamp light up. Now, the
power that the lamp uses is related to the electrons that come out of the wall. The current
is the rate of electron flow; that means that it’s the number of electrons that come up the
wire into the lamp in a given time. The voltage is the amount of energy each electron has
in it; higher voltage electrons have more energy. If you multiply the number of electrons
going through the wire (current) times the energy that EACH electron has (voltage), you
get the power or how much energy the lamp uses up. So electricity is electrons GIVING
ENERGY to a thing. Now you are all experts on electricity.
Now, let’s switch gears and learn about something completely different. We’re
going to watch a video from 1937. Did you know they made movies in 1937? It’s pretty
old. So sit and watch this video and we’ll talk about it afterwards. [show video of the
Hindenburg exploding. After the video, ask them to describe what happened. Especially
try to lead them to mention that the blimp was filled with Hydrogen and that’s what
burned. Try to lead them into an understanding of the properties of Hydrogen (low
density, colorless gas, flammable).] So the reason the blimp lit on fire was because of
hydrogen. And why did the flames go UP instead of down? [hydrogen is a less dense
gas than air] Okay, good.
So what is hydrogen? Lets learn some simple facts about it. [concepts to cover:
atomic number, protons, neutrons, electrons, periodic table, number of atoms in a
molecule, chemical formula] Hydrogen has three isotopes; regular Hydrogen (no
neutrons), Deuterium (one neutron), and Tritium (two neutrons). Deuterium and Tritium
are the “hydrogen” in a hydrogen (fusion) bomb. Hydrogen atoms make up about ¾ of
the visible universe (by mass).
Engineers have thought of a lot of different ways to use hydrogen (besides
making the Hindenburg float). They figured out that since hydrogen makes a lot of
energy when you burn it, you can use hydrogen gas to make an engine work (like the one
in your car) or you can use it to make a thing called a “fuel cell” work to make electricity.
Not only have engineers used hydrogen gas, they have used liquid hydrogen (which is
really, really cold) is used to launch the space shuttle (with liquid oxygen). And solid
hydrogen (Deuterium or Tritium) can be used for nuclear fusion to make a whole lot of
energy and turn the hydrogens into helium. [Use these concepts to address molecular
motion and solids, liquids, and gases]
So who figured out all this stuff? Well, like most old stuff in science, it was
discovered by dead white dudes. [give a brief history of hydrogen, in case students are
interested in that sort of thing] Hydrogen was discovered by a British guy (Henry
Cavendish) in 1766. Back then it was a pretty new concept that gases were different
from each other; they only just learned that air existed at all. He put zinc metal in
hydrochloric acid and collected the gas that it made. He wrote about how when he
burned the gas (lit a match and put it in) it made water. Later on (1788) a French guy
(Antoine Lavoisier) named the gas that Cavendish made “Hydro Gen”. In Latin,
“Hydro” means “Water” and “Gen” or “Genes” means “Made of” or “Born of”. So they
named it “The gas that makes water when you burn it”.
Now we know that you make water when you burn hydrogen. How would you
“un-burn” it? What could you do to make hydrogen if you had water? So here’s a
chemical reaction that might be able to do it [show pictogram of electrolysis] What this
diagram is showing is that electricity plus two waters is making two hydrogens and one
oxygen. [Explain this in detail to the students: mention that the reaction is balanced and
talk about the conservation of mass and how a reaction just rearranges atoms] So what is
this reaction depicting? Hint: its one of our vocabulary words. [Lead them to
electrolysis]
Lesson Background & Concepts for Teachers
The motivation for this lesson (which is part 1 of 2) is to educate students on the
use of hydrogen as an energy carrier / fuel. Hydrogen is sometimes referred to as the
“fuel of the future” because it emits no pollution (other than water) when it is reacted as a
fuel. In 2004, Gov. Schwarzenegger announced executive order S-7-04 creating the
“California Hydrogen Highways Network” (see http://www.hydrogenhighway.ca.gov/ ).
The plan he outlined mandated the creation by 2010 a “Hydrogen Highway” – a network
of hydrogen fueling stations approximately every 20 miles on major highways in
California – which will be able to fuel a fleet of Hydrogen-powered vehicles to travel
freely around the state. The vast majority of these Hydrogen-powered vehicles which are
currently in production run using Polymer Electrolyte Membrane (PEM) Fuel Cell
technology.
See http://www.hydrogenassociation.org/general/factSheets.asp for a lot of date
on hydrogen. Most hydrogen is produced by methane steam reforming (see part 2) but in
order to use renewable or sustainable energy sources to make hydrogen for fuel, it will
most likely require the electrolysis of water. Electrolysis is a process wherin an electrical
current (from a solar panel, windmill, water-driven or steam-driven turbine, etc.) is run
through water with some sort of electrolyte in it (to improve the electrical conductivity of
the water but not to react) to generate hydrogen gas at the negative electrode (anode) and
oxygen gas at the positive electrode (cathode). This process effectively stores the energy
from the electricity in the chemical bonds of the hydrogen and the oxygen so that it can
be used later in a device. Electrolysis is also used by engineers to manufacture raw
materials including chlorine gas and chlorine bleach (by running a current through brine
or salt water) and aluminum (via the Hall-Héroult process) and it is also used to
electroplate metals (by running a current through an object to be plated in a solution of
the plating metal’s salt).
More information on the Hindenburg disaster, taken from the Rocky Mountain
Institute’s “Twenty Hydrogen Myths” (Copyright © 2003 by Rocky Mountain Institute):
“An investigation by NASA scientist Dr. Addison Bain found that the
[1937 Hindenburg] disaster would have been essentially unchanged even if
the dirigible were lifted not by hydrogen but by nonflammable helium, and
that probably nobody aboard was killed by a hydrogen fire. (There was no
explosion.) The 35% who died were killed by jumping out, or by the
burning diesel oil, canopy, and debris (the cloth canopy was coated with
what nowadays would be called rocket fuel). The other 65% survived,
riding the flaming dirigible to earth as the clear hydrogen flames swirled
harmlessly above them. This would hardly be the case if an aircraft with
only liquid hydrocarbons caught fire while aloft. It emphasizes that
hydrogen is generally at least as safe as natural gas or LPG, and is arguably
inherently safer than gasoline, although the character of their risks is not
identical. For example, leaking hydrogen gas will accumulate near the
ceiling of an airtight garage, while gasoline fumes or propane will
accumulate near the floor - a greater risk to people because they’re
typically near the floor, not the roof. Standing in a carpet of fire is far more
dangerous than standing below a nearly non-luminous clear flame that goes
upwards.”
Hydrogen is the smallest element in existence. It is estimated that it makes up
three quarters of the baryonic matter in the universe by mass. It is not naturally occurring
on earth. Its nucleus has one proton and anywhere from zero to two neutrons. Elemental
hydrogen with one neutron is commonly called Deuterium and with two neutrons
Tritium. In its most stable state at room temperature and pressure, it exists as a diatomic
gas (H2) which is odorless, colorless, very low density, and very high diffusivity. It
reacts very rapidly with oxygen to produce water, hence its name from the Latin “Hydro”
(water) and “Genes” (born of). Hydrogen liquefies at 22 K and freezes at 14 K. It was
first liquefied by James Dewar (inventor of the vacuum flask) around 1898 and solidified
a year later (also by Dewar).
Hydrogen was discovered in 1766 by British scientist Henry Cavendish by
reacting zinc metal with hydrochloric acid and collecting the gas that evolved. This
discovery led to the further realization that water (H2O) is made of hydrogen and oxygen.
Antoine Lavoisier named it hydrogen in 1788. Two English scientists (William
Nicholson and Sir Anthony Carlisle) discovered that you can make hydrogen by running
an electrical current through water in 1800; this process is known as electrolysis.
Another English scientist, Sir William Grove, created the first fuel cell in 1845 which
reacted hydrogen with oxygen to produce water and electricity. Since that time there
have been many advances in hydrogen fuel cell technology; hydrogen fuel cells have
been used to power vehicles, components in the space shuttle, and commercial buildings.
Other applications of hydrogen include using solid hydrogen (deuterium / tritium)
as a point source for nuclear fusion by shooting a high intensity laser beam at the solid
and also as a liquid fuel in internal combustion engines or in jet engines like those on the
space shuttle.
You have to be flexible in what you want to cover, because you won’t get to
everything. Find something the students seem to be interested in (science-wise) and go
with it. During the lecture part of the lesson, I tried to change things up by incorporating
a video and some pictures of explosions. I tried to teach to what the students were
interested in, and that seemed to work fairly well. Concentrating on the concepts I
wanted them to learn (conservation of mass, atoms, elements, energy, protons, neutrons,
etc.) seemed to lead the students to ask better questions.
Image
Figure #1
ADA Description: List of energy sources that
can be used to generate hydrogen
Caption: Figure #1
Image file name:
HydrogenProductionRoutes.bmp
Source/Rights: Copyright © 2008 U.S.
Department of Energy
Vocabulary / Definitions
Word
Definition
Hydrogen
The smallest known element. Has one proton, one electron, and
from 0 to 2 neutrons.
Oxygen
Element number 8. Primary component of water (with hydrogen)
and second most common gas in the earth’s atmosphere
Fuel cell
A device which continuously reacts some fuel with an oxidant in an
electrolyte to make electricity
Chemical reaction
A process where elements or compounds undergo a chemical
change. In a reaction, atoms are rearranged into different
combinations of molecules.
Electrolysis
A chemical reaction which uses electricity to force the chemical
change in the reactants
Power
The rate at which energy is used in an electrical device
Voltage
A measure of the energy of the electrons in electricity
Current
The rate of electrons flowing in electricity
Proton
(use the definition from the students’ textbook)
Neutron
(use the definition from the students’ textbook)
Electron
(use the definition from the students’ textbook)
Physical property
(use the definition from the students’ textbook)
Chemical property (use the definition from the students’ textbook)
Atom
(use the definition from the students’ textbook)
Molecule
(use the definition from the students’ textbook)
Conservation of
(use the definition from the students’ textbook)
matter
Electrical
The measure of how well electrons flow through a material without
conductivity
losing their energy
Associated Activities
Activity # 1 Title: Electrolysis of water to make hydrogen and oxygen
Activity # 2 Title: Making electricity from hydrogen using PEM Fuel Cells
Lesson Closure
So what did we learn today? We learned that electricity is the flow of electrons and that
if you use electricity to make a chemical reaction go it’s called electrolysis. We learned
about the different physical and chemical properties of hydrogen and we learned that it
has a lot of energy in it (especially when there’s a lot of it like in the Hindenburg!) We
learned that engineers can design things that use hydrogen like engines, fuel cells, space
shuttle rocket boosters, nuclear fusion reactions, etc. and that hydrogen is mostly a gas
but that you can slow the molecules way down and make it into a liquid or solid if you
get it REALLY REALLY cold. We learned about the dead white dudes who discovered
hydrogen and why they named it “the gas that makes water”. And finally we learned that
we can use electricity to make hydrogen by putting it through water (REACTING with
the water to form hydrogen and oxygen gas).
Assessment
Pre-lesson:
Ask students if they can tell you the atomic number of a random element. Then ask them
what it means in terms of its protons, neutrons, and electrons. Ask students to solve
simple algebra problems like: if the density of water is 1 kg per liter and my faucet lets
out 1 liter of water per second, how many kilograms of water come out of my faucet per
second? After that example, you could ask what density is and what it means for gases
and liquids, how to measure liquids by volume, etc. And ask them what it means to burn
something [it means that the “something” is a fuel and reacts with an oxidant, almost
always oxygen gas, to make heat, light, and “new stuff”]
Post-lesson:
Ask / quiz students on how you can make hydrogen since it doesn’t exist on earth. Ask /
quiz them about properties of hydrogen (protons, electrons, possible number of neutrons,
atoms in a molecule of it, chemical formula, state of matter at room temperature and
colder temperatures, etc.) Ask them to define electrolysis and to give examples of how
we can use hydrogen. Ask them how to calculate power from current and voltage.
Lesson Extension Activities
1. Have the students do a written report on the Hindenburg disaster.
2. Have the students visit a hydrogen fueling station or see a fuel cell-powered car
3. Have students write a report on how using hydrogen as a fuel is different from
using gasoline as a fuel
Additional Multimedia Support
See attached powerpoint presentation and video of Hindenburg disaster. If you are using
the powerpoint presentation, include a photograph of the experimental setup for
electrolysis in your presentation.
References
National Hydrogen Association (lots of good general facts about hydrogen):
http://www.hydrogenassociation.org/general/factSheets.asp
Periodictable.com (pictures and descriptions of hydrogen samples):
http://periodictable.com/Elements/001/index.html
Facts on the California “Hydrogen Highway”:
http://www.hydrogenhighway.ca.gov/
More information on fuel cells and hydrogen:
http://www.rmi.org/sitepages/pid255.php
Hydrogen facts for kids from the U.S. Dept. of Energy:
http://www.eia.doe.gov/kids/energyfacts/sources/IntermediateHydrogen.html
Attachments
H2AsEnergyCarrierPartI.ppt
HindenburgExplodes1937.mp4
WaterPlusEtoH2plusO2.bmp
HydrogenProductionRoutes.bmp
Henry-Cavendish.jpg
Antoine-Lavoisier.jpg
Other
Redirect URL
Owner
UCLA SEE-LA GK-12 Program, University of California, Los Angeles.
Contributors
Benjamin Davis, Sue Robins, and Don Guthrie
Copyright